The rectifier is an electrical device that converts alternating current (AC) into direct current. Basically the direction of the alternating current is periodically reversed to produce the direct current. The direct current (DC) flows in only one direction.
The process of converting alternating current into direct current is known as rectification. It makes straightens the direction of the current.
Uses of the rectifier in different devices
Physically, rectifiers take a number of different forms, including mercury-arc valves, selenium oxide, stacks of copper and vacuum tube diodes plates, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches.
Even in history the synchronous motors and electromechanical switches have been used. Early radio receivers that also called crystal radios. It is used a cat’s whisker of fine wire pressing on a crystal of lead sulfide to serve as a crystal detector or point-contact rectifier.
Uses of the rectifier in different fields
Rectifiers have many uses in different fields. It also uses as high-voltage direct-current power transmission systems and components of DC power supplies. It also generates direct current that use as a source of power. Detectors of radio signals also serve as rectifiers. In gas heating systems the flame rectification is used to detect the presence of a flame.
Rectifier that depends on different types of alternating current
The rectification depends on the type of alternating current supply and the arrangement of the rectifier circuit. In both cases the output voltage may require additional smoothing to produce a uniform and steady voltage.
Many other applications of rectifiers, such as power supplies for computer, television and radio equipment, require a steady constant DC voltage that produces by a battery.
In all these applications the output voltage of the rectifier is smoothed by an electronic filter, which may be a choke, capacitor, or set of capacitors, resistors and chokes possibly followed by a voltage regulator to produce a steady output voltage.
The vacuum tube thermionic diodes and copper oxide- or selenium-based metal rectifier stacks were used, before the development of silicon semiconductor rectifiers. With the introduction of semiconductor electronics, the vacuum tube rectifiers became older, except for some enthusiasts of vacuum tube audio equipment.
On the basis of the current range, the power rectification goes from maximum to minimum current range. The semiconductor diodes are various types like junction diodes, Schottky diodes, etc. These are widely used in different fields.
Other control electrodes devices that acting as unidirectional current flow. These types of devices are used, where more than simple rectification is required. For example, where the variable output voltage is needed, we use these devices.
High power rectifiers, especially those used in high-voltage Direct-current power transmission, employ silicon semiconductor devices of various types. These are thyristors, transistors, relays or other controlled switching solid-state switches, which effectively function as diodes to pass the current only in one direction.
The primary application of rectifiers is to convert alternating current into direct current (AC to DC converter). Rectifiers are used inside the power supplies in all electronic equipment.
Alternating current or direct current power supplies may be broadly divided into linear power supplies and in switched-mode power supplies. In these power supplies, the rectifier will be connected in a series following the transformer, and be followed by a smoothing filter that possibly a voltage regulator.
Converting of DC to DC power from one voltage to another is much more complicated. One method of DC-to-DC conversion first converts power to AC by using an inverter, then uses a transformer to change the voltage, and then finally rectifies convert the power back to DC.
A frequency of typically several kilohertz is used, as this requires much low inductance than at lower frequencies and obviates the use of heavy, expensive and bulky iron-cored units.
This graph shows the output voltage of a full-wave rectifier with controlled thyristors.
- Rectifying a voltage, such as turning the AC into DC voltages.
- Isolating signals from a supply.
- Voltage Reference.
- Controlling the size of a signal.
- Mixing signals.
- Detection signals.
- Lighting systems.
- LASER diodes.